Feed collet



Patented Feb. 15, 1944 'UNITED STATES PATENT OFFICE FEED ooLLE'r Irvingn. Sheffer, Detroit, Mich.

Application September 17,1942, Serial No. 458,683

' .7 Claims. (01. 29--62) This invention relates to improvements in feedcollets by which rods or bars of stock are fed through the hollowspindles of automatic machines.

It is an object of the invention to provide a feed collet primarilyintended for handling larger, heavier stock, for to operatesatisfactorily the collet must, upon each forward movement, move thestock until the latter contacts a'stop in order that the same length ofstock projects at the commencement of each operation. Consequently afirm grip on the stock must be obtained in order to insure its fullmovement. To achieve this the feed collet includes two sets ofcircularly arranged feed fingers longitudinally spaced from one anotherto increase the total effective gripping area of the fingers upon thestock because there is a limit to the effective gripping area that canbe provided upon the separate fingers which are of course resilient andinwardly flexed towards the collet axis toward their free extremities.Moreover by providing a relatively large number of fingers asatisfactory grip may be obtained upon the stock even if its peripheryis somewhat irregular; and by providing one set offingers at the frontextremity of the collet the stock may be fed when it becomes quiteshort. Again the longitudinal spacing of the two sets of fingers assistsin maintaining the stock in a horizontal position so that it may be moreeffectively engaged by the fingers.

The invention also aims to provide a feed collet wherein the feedfingers are so arranged that they are readily separately adjustable sothat they may be pushed inwardly and re-set after the tool has been inuse to increase the life of the said tool; and the two sets of feedfingers may also be circularly staggered relative to one another both toincrease the strength of the tool and also to further increase itsgripping ability when handling somewhat irregular stock.

Having thus briefly and broadly stated some of the objects andadvantages of the invention I will now proceed to describe a preferredem-- bodiment thereof with the aid of the accompanying drawing, inwhich:

Figure 1 illustrates a longitudinal section of the collet with the feedfingers in the position they assume when gripping a bar of stock.

Figure 2 is a section on the line 22 of Figure 1.

Figure 3 is an end elevation on the line 33 these two portions is thesame.

the feed fingers flexed further inwardly into the I position they assumeprior to the insertion of a bar of stock; the latter however is alsoshown to more clearly bring out the additional flexing of the fingers.

Referring to the drawing, l designates a collet which is tubularthroughout its entire length and is provided at its adapter end 2 withmeans such as the screw thread 3 for attachment to a feed tubenot shown.In Figure 1 a collet is shown the adapter end of which is ofsubstantially the same diameter as that of the remainder of the toolwhereas in Figure 4 the adapter end is larger. The size of the adapterend of course depends upon the size of the feed tube to which it is tobe attached whereas the size of the remainder of the collet andparticularly its bore depends upon the size of the stock to be handled.

The collet I, both intermediately of its length and from its frontextremity remote from the adapter end 2 is provided with portions 4 and5 respectively of reduced bore; and the bore of Formed longitudinally inthe collet l and extending preferably beyond the ends of theintermediate bore portion 4 are a plurality of slots 6 each adjacentpair of which is connected at its front extremities by a cross slot 1 sothat each pair of slots thus connected by their cross slot define threesides of an intermediate feed finger 8, and between each of the latterthe front and rear extremities of the. collet are connected by integralribs 9 which of course extend between adjacent pairs of unconnectedslots 6. The collet is also longitudinally slotted at II! from its frontextremity through its front reduced bore portion 5 to form front feedfingers l I which are forwardly spaced from the intermediate feedfingers 8 and the cross slots 1. These fingers 8 and II, which are ofcourse resilient are then forced inwardly sufiiciently to grip the stockA extending through the collet and hold the said stock clear of theinner sides of the ribs 9.

It may here be noted that while the stock A is indicated in all theviews its insertion in Figure 4 is merely to more clearly show theadditional inward flexing of the feed fingers 8 and II when the stock isnot there as obviously the fingers could not project inwardly beyond theperiphery of the stock.

The slots in in the front reduced portion 5 are preferably disposedsubstantially centrally between adjacent pairs of slots 6 and are ofcourse forwardly spaced from the latter. By this arrangement greaterstrength is afforded to the tool, and a more satisfactory grip may alsobe obtained upon stock having a somewhat uneven periphery. Again due tothe fact that a rib 9 extends between each adjacent pair of intermediatefeed fingers 8 whereas front fingers H only are provided by the frontextremity of the collet the number of front fingers may be double thatof the number of the intermediate fingers. By thus providing a largenumber of feed fingers the effectiveness and life of the tool isincreased, and the fingers themselves are all so arranged that they maybe easily and quickly re-set to prolong the life of the collet.

It will also be noted that both extremities of front and intermediatereduced bore portions -4 and 5 are chamfered at l2 to prevent anybinding action relative to the stock particularly when the collet isbeing moved independently of the latter.

While in the foregoing the perferred embodiment of the invention hasbeen described "and tremity and intermediately of its length to form 5.front and intermediate integral feed fingers which arelongitudinallyspaced from. one another, and said fingers being inwardly flexed to--ward the axis of the tubular member.

2. A feed collet comprising a tubular member provided at, its rearextremity with means for attachment to a feed tube, said member beinglongitudinally slotted intermediately of its length and having crossslots formed therein connecting the front extremities of adjacent pairsof the intermediate slots, intermediate feed fingers integral with themember each having three sides defined by each pair of connected slotsand their cross slot, and said. member being longitudinally slotted fromits front extremity to divide that extremity'into a plurality of frontfeed fingers,

the rear extremities of the front slots being forwardly spaced from saidcross slots, and said-feed fingers being inwardly flexed toward the axisof the member.

3. A feed collet including the combination set forth in claim 1 whereinthe front slots are circumferentially offset relative to theintermediate slots.

4. A feed collet comprising the combination set forth in claim 1,wherein the intermediate portion of the bore through which theintermediate slots extend and the front extremity of the bore are ofsomewhat smaller diameter than the remainder of the bore, and the feedfingers are sufliciently inwardly flexed to support stock clear of theintermediate bore portions which extend between the intermediate feedfingers.

-5. A feed collet comprising a tubular member provided atv its rearextremity with means for attachment to a feed tube, said member beingslotted longitudinally both from its front extremity and intermediatelyof its length forming front and intermediate integral feed fingersbetween-them, thefront. and intermediate fingers .flnsers are formed btw n adjacent pa rs of slots, the bore of the slotted portionsvbein oflesser diameter than the bore of theremainder of the member, he frontextremities of the intermediateslots being spaced rearwardly from th rar ex remiti s of th fronths tsh and sa d member having cross slotsformed therein each 1 connecting the front extremities of two adjacentintermediate slots.

7, A feed collet including the combination set forth in claim 6, whereinthe front slots are circumferentially offset relative to theintermediateslots.

IRVING .H. SHEFFER.

